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外源新碳加入土壤后,传统技术尚无法区分其与原土壤有机碳的不同。利用13C稳定同位素方法,通过室内培养实验,探讨玉米秸秆和根茬添加到不同肥力水平土壤后外源新碳在土壤中分配与固定的差异。结果表明:(1)低肥土壤添加叶28 d后土壤有机碳(SOC)含量高于添加根和茎的;高肥土壤添加叶在整个培养期间(1~180 d)SOC含量都高于添加根和茎;两种肥力水平土壤在添加玉米根、茎、叶180 d后SOC含量均接近相等。(2)玉米根、茎、叶的添加对SOC中外源新碳含量以及残体残留率的影响不同,28 d前低肥土壤外源新碳含量高于高肥土壤,28 d后结果与之相反;低肥土壤在培养28 d后添加根的残留率比添加茎和叶的低,高肥土壤在培养7 d后添加叶的残留率比添加根和茎的低。以上结果表明,外源新碳在土壤中的固定受其来源和土壤肥力水平的影响与制约。
After the introduction of new source of new carbon into the soil, the traditional technology can not distinguish between the original soil and organic carbon. The 13C stable isotope method was used to study the difference of distribution and fixation of new exogenous carbon in soil after adding corn stalks and stubble to soil with different fertility level. The results showed that: (1) Soil organic carbon (SOC) content in low-fat soil after 28 days was higher than that in roots and stems; SOC content in high-fat soil added leaves was higher than that in the whole incubation period Roots and stems. SOC content of two soil fertility soils after 180 d of adding corn roots were nearly equal. (2) The effect of corn roots, stems and leaves on the new and exogenous carbon content and the residual rate of residuals in corn was different. The content of exogenous fresh carbon in low-fat soil before 28 d was higher than that in high-fat soil. After 28 days, On the contrary, the residual rate of roots added in low-fat soils after 28 days of culture was lower than that of stems and leaves, and the residual rate of added leaves in high-fat soils after 7 days of culture was lower than that in roots and stems. The above results show that the new exogenous carbon fixation in the soil by its sources and soil fertility levels and constraints.